Bengal Engineering and Science University 2006 B.E Computer Science and Engineering Operating system principles - Question Paper
the ques. paper is with the attachment.
BE CST 6th Semester Examination, May 2006
Computer Science & Technology Dept.
Operating System Principles (CST - 602)
F.M.: 100 TIME : 3 hrs
Attempt any 3 questions from the first half, Question No. 6 from the second half and any two from the rest of the second half.
Two marks in each half are reserved for clarity of presentation.
Use separate answer book for each half.
Answers should be in your own words as far as practicable.
Make your own assumptions as and when necessary and state them at proper places.
1. (a) What do you understand by i) waiting time ii) response time? 2+2
(b) Describe the basic principle of Lottery Scheduling. 6
(c) Discuss the significance of i) Ticket Transfer ii) Compensation Tickets 3+3
2. (a) State the Bakery algorithm. 4
(b) Show that all the three requirements for a solution to critical section problem is preserved in the above algorithm. 6
(c) Propose a starvation free solution to Readers-Writers problem using semaphores.
6
3. (a) Describe the 50-percent rule. 2
(b) Write short notes on i) PTLR ii) TLB 3+3
(c) Describe the working principle of Inverted Page Table combined with the Hash Anchor Table (HAT). 5
(d) Why is HAT used with Inverted Page Tabled 3
4. (a) Describe the benefits of demand paging. 3
(b) Write short notes on i) pure demand paging ii) prepaging 2+2
(c) Describe the role of the following bits in demand paging:
i) reference bit ii) modify bit iii) valid-invalid bit 2+2+2
(d) Discuss how a process creation using forkQ system call can be optimized in demand paging environment. 3
5. (a) Given that: i) TLB hit ratio: 0.88 ii) TLB access time: 20 ns iii) Memory access
time: 110 ns iv) Two level paging architecture v) Page fault service time: 25 ms vi) Page-fault rate: 0.0000001 (1 in a million)
i. Find out the effective memory access time in the above demand paging envi ronment.
6
ii. Compare this time with the effective memory access time of normal paging (without demand paging) environment.
(b) What is thrashing?
4
(c) How can you prevent thrashing in a system? 4
6. Write short notes on the following.
(a) The uniform interface provided by the Device Drivers to the rest of the Kernel.
(b) Filesystem Integrity and its checking.
(c) Block size and fragmentation in a filesystem.
(d) Domain of Protection
7. (a) Consider the command "cp filel file2' under unix operating system to copy a file
filel to another file fle2, Explain how different modules of the kernel is involved to execute this command.
(b) Mention the objectives to be fulfilled while designing the organization of files and directories in a filesystem.
(c) Explain with example(s) what you mean by data and metadata in the context of file system. How are they managed?
(d) Explain with example(s) what you mean by trap-door, Trojan Horse, worm and virus in the context of security.
8. (a) Explain why files and open files are treated separately within the kernel.
(b) Explain how device files in Unix enable us to use the same file-interface over in put/output devices.
(c) Describe different strategies to maintain protection information in the operating system along with their merits and demerits.
9. (a) Present a comparative study between deadlock prevention and avoidance.
(b) "Presence of a cycle in the resource allocation graph in a system with multiple instances of resources does not necessarily indicate a deadlock." - Explain with example(s).
(c) Explain the different approaches for deadlock recovery along with their merits and demerits.
[6+5+5]
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Attachment: |
| Earning: Approval pending. |
